A new study has found that nasal decongestants such as Sudafed may increase the risk of certain rare birth defects when taking during the first trimester of pregnancy. Researchers found that some types of over-the-counter decongestants such as phenylephrine and pseudoephedrine were associated with rare birth defects that cause abnormalities in the digestive tract, ear and heart. The study was conducted by Allen Mitchell and his team at the Slone Epidemiology Center at Boston University.

Mitchell, who is the director of the Slone Epidemiology Center, pointed out to Reuters that major birth defects affect approximately two to three percent of liveborn infants, which is rare. He said that the defects focused on in the study “generally affect less than 1 per 1,000 infants. Some of them may require surgery, but not all are life-threatening.” Still, he said that “The fact that medications such as decongestants are typically and widely available for use without a prescription and do not require consultation with a healthcare provider should not be assumed to mean they are safe with respect to the fetus, since there are still relatively few studies that examine the risks and relative safety of these ‘over-the-counter’ medications, which are more widely used in pregnancy than prescription medications,”

The study confirmed previous research suggesting that phenylephrine, which is used in Sudafed, and Acutrim, which contains phenylpropanolamine, is linked to birth defects. The authors found that phenylephrine is linked to an 8-fold increased risk of a heart defect called endocardial cushion defect when taken during the first trimester. Similarly, first trimester use of phenylpropanolamine, was associated with an 8-fold increased risk of ear and stomach abnormalities.

The study also had novel findings. For the first time, research showed that first trimester use of pseudophedrine (another Sudafed ingredient) was associated with a 3-fold higher risk of limb reduction defects. Use of imidazoles, which is found in nasal decongestant sprays and eye drops, was linked to a doubled chance of an abnormal connection between the trachea (airway) and esophagus.

The study analyzed data from 12,700 infants born with non-chromosomal birth defects between 1993 and 2010 compared to 7,600 infants without deformities. According to Mitchell, the research is enough for doctors to not prescribe nasal decongestants to women, but this should be determined on an individual basis.